Flashlamp

ABSTRACT

A percussive-type flashlamp has a glass envelope, a metal base sealed to one end and having a cup portion extending from it, with an anvil fitted into said cup by crimping or the like, the anvil having a cylindrical portion terminating at one end in a flat annular rim seated at the flat bottom of the cup and having a concave portion to form an enclosed cavity with said flat bottom of the cup. This construction provides a rigid anvil which will hold firm against the action of the firing pin, and which forms a cavity for a percussive charge, the opposite flat portion of the cavity being held with a precise spacing between them. The end of the cylindrical portion of the anvil terminates in a flaring shield which spreads out to the inner diameter of the envelope to protect the metal base from molten metal particles, or agglomerates of particles, from the foil of shredded metal, for example of zirconium, with which the envelope is filled. There is also a filling of oxygen at high pressure in the envelope, which is sealed.

United States Patent Kopelman et al.

[ FLASHLAMP [7 2] Inventors: Bernard Kopelman, Salem; Warren H. Hay,Beverly, both of Mass.

[73] Assignee: Sylvania Electric Products, Inc.

[22] Filed: April 6, 1971 211 Appl. No.: 131,802

Related US. Application Data [63] Continuation of Ser. No. 662,755, Aug.23, 1967,

FOREIGN PATENTS OR APPLICATIONS 431,953 7/1935 Great Britain ..43l/93Primary Examiner-Edward G. Favors Att0rneyNorman J. OMalley and LaurenceBurns [57] ABSTRACT A percussive-type flashlamp has a glass envelope, ametal base sealed to one end and having a cup portion extending from it,with an anvil fitted into said cup by crimping or the like, the anvilhaving a cylindrical portion terminating at one end in a flat annularrim seated at the flat bottom of the cup and having a concave portion toform an enclosed cavity with said flat bottom of the cup. Thisconstruction provides a rigid anvil which will hold firm against theaction of the firing pin, and which forms a cavity for a percussivechargefthe opposite flat portion of the cavity being held with a precisespacing between thcm. The end of the cylindrical portion of the anvilterminates in a flaring shield which spreads out to the inner diameterof the envelope to protect the metal base from molten metal particles,or agglomerates of particles, from the foil of shredded metal, forexample of zirconium, with which the envelope is filled. There is also afilling of oxygen at high pressure in the envelope, which is sealed.

3 Claims, 1 Drawing Figure 1 m 2 M 5 H Y 6 PA 0 OH K 7 DH 3 R A m 3 H BWINVENTORS ATTORNEY PATENTED llEc 19 I972 FLASHLAMP This application is acontinuation of application Ser. No. 662,755 filed Aug. 23, 1967 and nowabandoned.

FIELD OF INVENTION This invention relates to photographic flashlarnpsand the like of the type fired by the action of a firing pin on apercussive detonator, thereby eliminating the need for the electricbattery used with the prior type of commercial flashlamp.

DESCRIPTION OF PRIOR ART In the percussive type lamp, an envelope oflighttransmitting glass is sealed at one end to a cup, usually of metal,which closes off one end of the tube and supports an anvil which fits onthe bottom of the cup, leaving space for the percussive charge. Theglass envelope has a filling of the usual shredded foil or the like,generally of zirconium metal. In operation, when the outside cup isstruck by a firing pin, the percussive charge is forced against an anviland detonates, heating up numerous particles of metal, such aszirconium, which are mixed with it, and shooting them through holes inthe anvil into the shredded foil or the like, setting it off to burn inthe oxygen with which the envelope is filled to a high pressure.

SUMMARY OF THE INVENTION The metal base which sealed off the bottom ofthe glass tube should be easily deformable by a firing pin so that alarge part of the energy of the pin is available to set off thepercussive material; moreover, the base should also be capable of beingsealed to a glass envelope with a minimum of strain and with sufficientstrength to withstand the normal high fill gas pressure as well as thevery high pressure built up during the flash; and it should be capableof being easily fabricated at low cost on high speed machinery.

We have discovered that such a base can be made of the so-called No. 4alloy metal for scaling to soft glass, although any metal which can besealed with a strong bond to the glass can be used and if sufficientlydeformable would be suitable. The cup is in a shape having an open rimfor sealing to the glass, the rim having a taper narrowing toward theopen end forming a frustrum of a cone and terminating at its other endon a flat, annular portion from the center of which a cylindrical cupextends downwardly to be closed by a substantially flat closure member,generally integral with the cup. The tapered rim insures good contactwith the glass. The flat closure member is the portion of the base to bestruck by the firing pin and the flat surface lies parallel to the flatanvil to be described. The percussive material is confined between thesesurfaces.

The anvil, which can be of metal, is inserted into the cup. We havediscovered that the anvil can be flat in its effective region ratherthan pointed, in order to allow for greater variation in the strikingposition of the firing pin, but the spacing between the anvil and thebottom of the cup must be held very uniformly from lamp to lamp to lamp.The bottom of the anvil should have some holes through which the hotmetal particles from the percussive mixture may travel upwardly to setoff the shredded zirconium foil, or similar material. We have discoveredthat the smaller these holes are made the smaller is the likelihood ofmolten zirconia globules, from burning shreds, burning through thebottom of the metal base.

We have further discovered that these hot globules can burn through themetal of the base around the anvil, and that this can be prevented byflaring out the open end of the cylindrical portion of the anvil untilit extends substantially to the inside of the envelope wall, to form ashield between the shredded metal foil and the metal base. The shieldshould be capable of being slipped into the inside of the envelope,which is tubular.

We have found that the anvil must be held rigidly and not deform muchfrom the energy of the striking pin.

We have discovered that these results can be achieved by an anvil havingits bottom portion concave, with a flat rim, and a cylindrical portionextending backwardly from the rim, the other end of the cylindricalportion being flared out to act as a shield for the cup. The concavenature of the anvil increases the resistance of the piece to deformationby the pin, and by making the central portion of the concavity flat,while the rim of the anvil seats on a flat portion of the cup, thedistance between the bottom of the cup and the flat top of the cavity isfixed, and the spacing does not depend on the precision of the person ormechanism attaching the cup and anvil together.

In addition, the anvil so made can be of thinner metal because of theshorter span of the concavity. This, in turn, allows the holes in theanvil to be punched, rather than drilled, and they can consequently bemade much smaller.

If it is desired to insure still further against any burn through of themetal cup from the hot' particles of metal, a copper or nickel wafer canbe placed at the bottom of the metal cup and held in place by the rim ofthe anvil.

The cylindrical portions of the cup and the anvil can be held togetherby crimping.

BRIEF DESCRIPTION OF DRAWING Other features, advantages and objects ofthe invention will be apparent from the following specification, takenwith the attached drawing in which:

The Figure is a cross-sectional view of a flashlamp embodying theinvention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS In the Figure, the glassenvelope 1 is sealed at its otherwise open end 2 to a metal base 3having an inwardly-flared rim 4 which engages the glass envelope. Thebase has a flat annular portion 5 and a convexly protruding cup 6 with aflat bottom 7. Resting on this bottom 7 is the rim 8 of the anvil 9,said anvil having a concave portion 10 with slanting or curved sidesextending inwardly from the rim of the anvil as a whole, to terminate ina substantially flat portion 11. The cylindrical surface 12 of the anvilfits into the cup 6 and the two are crimped together at 13.

The anvil is thus rigidly held to the cup 6 and the distance between theflat bottom 7 of cup 6 and the flat top 11 of anvil 9 is fixed. The rim8 of the anvil being flat and in contact with the flat bottom 7 of cup 6confines the percussive mixture 14 to a small volume at the center ofthe cup, which reduces the amount of the mixture needed and keeps it ina confined space, thereby getting full effect from it.

The flared-out shield at the top of anvil 9 extends outwardly andupwardly to shield the seal from hot metal particles which mightotherwise hit it with deleterious effect.

The shredded foil 16 is the usual material with which modern flashbulbsare filled, for example, shreds of zirconium. The envelope 1 is filledwith oxygen at a high pressure, say about 6 atmospheres, in the usualmanner, the envelope being sealed off at the exhaust tube 17 at the topof the envelope 1.

ln using the words top and bottom" with reference to the device of thisapplication, we mean top and bottom as in the drawing, that is, with thedevice held with the base 3 down and the exhaust tip 17 in a verticaldirection. I

The anvil 9 has a number of holes in its fiat surface, so that when thepercussive mixture is set off, hot particles of metal will be shotthrough the holes to reach the shredded foil 16 and set it off.

In one embodiment of the invention, the anvil 9 was of 0.010 inch metalstock, the cylindrical portion being about 0.145 inch outside diameterand about 0.155 inch in length. The open portion was fiaredvto a radiusof about one-sixteenths inch, the outside diameter of the flare beingabout 0.285 inches. The glass envelope was a tube about 0.290 inchesinside diameter, and 0.350 inches outside diameter, sealed at one end byan exhaust tube. The length from the rounded top of the envelope,exclusive of the exhaust tip, to its open end was about 1 inch.

The base had a maximum outside diameter of about 0.400 inches, with theopen end tapering to about 0.356 inches, the cup having an insidediameter of about 0.146 inches, with the outside length of the cup beingabout 0.150 inches.

The anvil 9 can be made of low carbon steel or other suitable material.The No. 4 alloy mentioned above as a material of which the base 3 can bemade is well-known in the art for sealing to the soft lead glass,generally known as 6-1 glass, of which the envelope 1 can be made. No. 4alloy is a nickel-chromium steel of about 42 percent nickel, 6 percentchromium and the remainder iron.

Various modifications will be apparent to a person skilled in the artwithout departing from the spirit and scope of the invention, and theinvention is not limited to the specific embodiment described, but isset forth in the claims.

A suitable percussive mixture is that shown in a patent application Ser.No. 662,756 of B. Kopelman and D. Seeger for a Photoflash Lamp andComposition therefor, filed Aug. 23, 1967 now abandoned.

We claim:

l. A percusive-type flashlamp comprising a glass envelope sealed at itsotherwise open end to a metal base closingit, said base having a cupextending outwardly therefrom, an anvil in said cup defining therewith acavity in which percusive material can be placed, said anvil having aflat rim fitting against the bottom of said cup and a concave portionwith a flat top portion inside said rim, and percusive material in saidcavity, and in which the anvil includes a metal cylinder having one endclosed by said fiat annular rim with a concave tron inside said rim,said concave portion having a t lz tt inner span, and a flared portionextending upwardly and outwardly from the metal cylinder toward the sideof the glass envelope.

2. A percusive-type flashlamp having a metal base, an enclosingtransparent envelope afixed thereto, a filling of metal shreds in saidenvelope, and an anvil therein, and a metal shield, said shield beingflared from the anvil to a diameter nearly as great as the insidediameter of the envelope, to protect the metal base from molten metalparticles from the filling.

3. A percusive-type flashlamp comprising a glass envelope sealed at itsotherwise open end to a tubular metal piece closing it, a filling ofmetal shreds in said envelope, and an anvil in said metal piece, saidanvil having a shield above said tubular piece and in position to shieldsaid piece from molten metal particles from the filling.

1. A percusive-type flashlamp comprising a glass envelope sealed at itsotherwise open end to a metal base closing it, said base having a cupextending outwardly therefrom, an anvil in said cup defining therewith acavity in which percusive material can be placed, said anvil having aflat rim fitting against the bottom of said cup and a concave portionwith a flat top portion inside said rim, and percusive material in saidcavity, and in which the anvil includes a metal cylinder having one endclosed by said flat annular rim with a concave portion inside said rim,said concave portion having a flat inner span, and a flared portionextending upwardly and outwardly from the metal cylinder toward the sideof the glass envelope.
 2. A percusive-type flashlamp having a metalbase, an enclosing transparent envelope afixed thereto, a filling ofmetal shreds in said envelope, and an anvil therein, and a metal shield,said shield being flared from the anvil to a diameter nearly as great asthe inside diameter of the envelope, to protect the metal base frommolten metal particles from the filling.
 3. A percusive-type Flashlampcomprising a glass envelope sealed at its otherwise open end to atubular metal piece closing it, a filling of metal shreds in saidenvelope, and an anvil in said metal piece, said anvil having a shieldabove said tubular piece and in position to shield said piece frommolten metal particles from the filling.